Halford stuff is made by Comma, I believe. If it meets the spec, it meets the spec . Don't forget the VW air-cooled engine design is only one step away from an 18th century threshing machine, so anything of the right grade will do, even Lidls special...
There was a good argument for semi synthetic posted some time ago. Can't remember much about it or who posted it. It just made sense when I read it!
Another vote for Halfords Classic 20w50. I had to ask when we first got our van (2 litre type 4 engine). The previous owner suggested it, as did several folk on here. http://www.halfords.com/motoring/engine-oils-fluids/engine-oil/halfords-classic-oil-20w50-5l Not (that) cheap - but they're open on Sunday... You'll also need an oil filter. Halfords HOF202 is the correct one for a type 4. http://www.halfords.com/motoring/car-parts/filtration/oil-filters/halfords-oil-filter-hof202
I have 20/50 in mine while I run it in, but then I'll be using 15/40. 20/50 also if your engine is tired. Not sure about 5/40 mentioned above, air-cooled engines oil temps vary wildly even over one journey and the tolerances to cope with this are agricultural by todays standards.
